The instant invention resides in the art of apparatus for raising and harvesting aquaculture. Particularly, a first portion of the invention relates to a pond structure and design in which aquaculture may be raised. The second portion of the invention relates to a device by which such aquaculture may be harvested from the pond.
Heretofore in the art, a large number of devices have been developed for utilization in retrieving shrimp, oysters, prawn, and the like from the sea. The most pertinent prior art teachings known to applicant are those of U.S. Pat. No. 3,608,217, wherein a plurality of teeth are used for stirring up the waters' bed for the purpose of catching oysters. The device is adapted to be towed by a tongue and is dragged along the ocean floor by means of skids. Further teachings of general interest in the art are those shown in U.S. Pat. Nos. 255,561; 297,079; 1,336,203; 1,959,793; 3,651,595; 3,775,891; and 3,777,388. While all of these prior art teachings relate in general to apparatus for harvesting aquatic life from the ocean, none of them are seen as bearing directly upon the novel features of the harvester presented as part and parcel of the invention herein.
The prior art also teaches the utilization of man-made ponds or pools for raising shrimp, prawn, and the like, and from which such aquatic life may be harvested for market. Such man-made pools allow the cultivation of such aquatic life in a substantially controlled environment and in a confined area from which harvesting is less time consuming and expensive than from the sea itself. Indeed, aquaculture, or the cultivation of aquatic organisms under conditions monitored and maintained by man, has become quite a profitable industry in the area of freshwater prawns, marine shrimp, and certain species of marine and freshwater fish. The ponds constructed for such aquaculture have tended toward large rectangular shapes covering an area of 0.5-3.0 acres. Typically, the water depths of such ponds have run 3-4 feet, with the ponds being excavated in earthen soil of a nature capable of retaining water. While such ponds have proved suitable for raising the aquaculture, removal of the marketable animal from the pond has proven to be rather expensive and time consuming.
In conventional rectangular shaped ponds, the harvesting technique requires that four or more persons enter the pond with a seine net. To keep the seine net vertical in the water, it is buoyed on top and weighted on the botton. The net is placed around the periphery of the pond and walked slowly toward one of the pond corners. This concentrates the animals into a small area where they can be removed and placed in containers for marketing. The harvest rate for a person operating in this manner has been calculated to be 0.75 acre per hour. Not only is this method of harvesting time consuming, it is also inefficient in that many of the animals escape the net by forcing their way under the weighted bottom or by securing themselves in depressions or holes in the floor of the earthen pond. These holes or depressions are caused by the intrusion of people walking the seine net about the pond.
Another method of harvesting animals from such ponds is that known as drain harvesting. Ponds adapted for such technique are provided with a bottom sloping to a drain which is used for evacuating the water from the pond, leaving animals stranded about the drain for ready retrieval by laborers. While this technique is very effective for removing animals from the pond, the equipment and energy necessary for draining and filling the ponds is expensive. Further, many cultured species have different growth rates, reducing the effectiveness of drain harvesting because only a certain portion of the total population of pond animals are, at any given time, of marketable size.